<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <script type="text/javascript" src="jquery.min.js"></script>
    <script type="text/javascript">
        var num = 0;  // 定义第一个输入的数据
        function jsq(num) {
            //获取当前输入
            if(num=="%"){
                document.getElementById('screenName').value=Math.round(document.getElementById('screenName').value)/100;
            }else{
                document.getElementById('screenName').value += document.getElementById(num).value;
            }
        }
        function eva() {
            //计算输入结果
            document.getElementById("screenName").value = eval(document.getElementById("screenName").value);
        }
        function clearNum() {
            //清0
            document.getElementById("screenName").value = null;
            document.getElementById("screenName").focus();
        }
        function tuiGe() {
            //退格
            var arr = document.getElementById("screenName");
            arr.value = arr.value.substring(0, arr.value.length - 1);
        }
    </script>
    <style>
            /*Basic reset*/
        *{
            margin:0;
            padding:0;
            box-sizing: border-box;
            font:  14px Arial,sans-serif;
        }
        html{
            height:100%;
            background-color:lightslategrey;
        }

        #calculator{
            margin: 15px auto;
            width:330px;
            height:400px;
            border: 1px solid lightgray;
            background-color:darkgrey;
            padding:15px;
        }

        /*LOGO*/
        .LOGO{
            height:20px;

        }
        .LOGO .name{
            float:left;
            line-height:30px;
        }
        .LOGO .verson{
            float:right;
            line-height:30px;
        }
        /*screen*/
        #shuRu{
            margin-top:15px;
        }
        .screen{
            margin-top:5px;
            width:300px;
            height:40px;
            text-align: right;
            padding-right:10px;
            font-size:20px;
        }
        #keys{
            border:1px solid lightgray;
            height:223px;
            margin-top:25px;
            padding:8px;
        }
        #keys .last{
            margin-right:0px;
        }
        .footer{
            margin-top:20px;
            height:20px;
        }
        .footer .link{
            float:right;
        }

        #keys .buttons{
            float:left;
            width: 42px;
            height: 36px;
            text-align:center;
            background-color:lightgray;
            margin: 0 17px 20px 0;
        }
    </style>
</head>
<body>
<div id="calculator">
    <div class="LOGO">
        <span class="name">简单的计算器</span>
        <span class="verson">@walker</span>
    </div>
    <div id="shuRu">
        <!--screen输入栏-->
        <div class="screen">
            <input type="text" id="screenName" name="screenName" class="screen">
        </div>
    </div>
    <div id="keys">
        <!-- j -->
        <!--第一排-->
        <input type="button" id="7" onclick="jsq(this.id)" value="7" class="buttons">
        <input type="button" id="8" onclick="jsq(this.id)" value="8" class="buttons">
        <input type="button" id="9" onclick="jsq(this.id)" value="9" class="buttons">
        <input type="button" id="Back" onclick="tuiGe()" value="Back" class="buttons">
        <input type="button" id="C" onclick="clearNum()" value="C" class="buttons" style="margin-right:0px">
        <!--第二排-->
        <input type="button" id="4" onclick="jsq(this.id)" value="4" class="buttons">
        <input type="button" id="5" onclick="jsq(this.id)" value="5" class="buttons">
        <input type="button" id="6" onclick="jsq(this.id)" value="6" class="buttons">
        <input type="button" id="*" onclick="jsq(this.id)" value="X" class="buttons">
        <input type="button" id="/" onclick="jsq(this.id)" value="/" class="buttons" style="margin-right:0px">
        <!--第三排-->
        <input type="button" id="1" onclick="jsq(this.id)" value="1" class="buttons">
        <input type="button" id="2" onclick="jsq(this.id)" value="2" class="buttons">
        <input type="button" id="3" onclick="jsq(this.id)" value="3" class="buttons">
        <input type="button" id="+" onclick="jsq(this.id)" value="+" class="buttons">
        <input type="button" id="-" onclick="jsq(this.id)" value="-" class="buttons" style="margin-right:0px">
        <!--第四排-->
        <input type="button" id="0" onclick="jsq(this.id)" value="0" class="buttons">
        <input type="button" id="00" onclick="jsq(this.id)" value="00" class="buttons">
        <input type="button" id="." onclick="jsq(this.id)" value="." class="buttons">
        <input type="button" id="%" onclick="jsq(this.id)" value="%" class="buttons">
        <input type="button" id="eva" onclick="eva()" value="=" class="buttons" style="margin-right:0px">
    </div>
    <div class="footer">
        <span class="aside">欢迎使用JavaScript计算器</span>
        <span class="link">
                <a href="#" title="声明" target="_blank">反馈</a>
            </span>
    </div>
</div>
</body>
</html>